Objectives: 1. The purpose of a portion of this investigation is to continue previous research concerning ultramicroscopic alterations in corneal cells during the graft versus host reaction. We are trying to find morphological expression of early cell injury caused by sensitized lymphocytes. At the present time our studies show that there are lytic changes in cultured stromal and endothelial cells, however they have not been consistent and the study demands a large number of serial ultramicroscopic sections. The methods used to carry on this research have been outlined in a previous application. 2. This part of the project concerns the study of selected pathological corneal material obtained at the time of surgery, ie: failed corneal grafts and opaque corneas due to endothelial disease, intraocular inflammation or infection. Due to the large number of corneal diseases seen in our clinics, the opportunity to study some pathological material is excellent. Papers have been written describing the changes in failed grafts and in bullous keratopathy. Due to space limitations these papers will not have the large number of illustrations intended; however, I am planning to put all this material together in a future monograph. 3. Research is also needed in the area of endothelial alterations due to lens emulsification or fragmentation, as done clinically for cataract extraction. Two machines will be available: the Cavitron-Kelman and the Shock instrument. The surgical procedure will be done in cats, rabbits and monkey eyes, and also in an occasional human eye which is freshly removed for reasons other than corneal disease. Nitroblue tetrazolium stain, scanning and transmission electron microscopy will be performed.